Centrifugal fan and pump.



s. C. DAVIDSON. CENTRIPUGAL FAN AND PUMP. APPLICATION FILED NOV. 17, 1913.

1,11O5,967. Patented Aug. 4, 1 91L B SHEETS-SHEET 1.

Eig. 2.

S. C. DAVIDSON.

GBNTRIPUGAL PAN AND PUMP.

APPLICATION FILED Nov. 17, 1913* 1,1055967, Patented Aug.4,1914.

2 SHEETS-SHEET 2.

@MKM @mf/r. .ZJ/IQUA) m the peculiar UNTED STATES PA'lllllN'II OFFICE.

SAMUEL CLELAND DAVIDSON, 0F BELFAST, IRELAND.

CENTRI'FUGAL FAN AND PUMP.

Specification. of Letters Patent.

Application iled November 17, 191B. Serial No. 801,446.

Patented Aug. 4, 1914i.

This invention refers to centrifugal fans. `and pumps of the incased type, and relates to an improved construction lof the casing for further utilizing, in practical operation,

phenomena described in a previous U. S. A. application of 25th September 1912, Ser. No. 722,220, which patent 1s hereinafter referred to as my prior patent. In my said prior patent, I have described certain phenomena, whereby when the fan 1s rotating within a concentric or a spiral 1nclosing casing of ordinary construction, the air discharged from what is referred to as the. positive ends of the fanblades, passes across, Iand in part renters the fan wheel centripetally at the negative end of the blades, the central part of the blades between tlie negative and positive ends being referred to as the neutral polnt. In my said- .prior patent, means are described where-by that part of the air which enters centripetally through the negative part of the blades was mainly taken from the suction side of the fan wheel, and in some of the described arrangements an additional volume of ail' passes by induction over the outside of the periphery of theblades., from the suction side into, and combines with the air discharging from the positive end of the fan wheel, without passing directly through the fan wheel at all.

A casing made in accordance with this invention may have that portion which lies beyond the periphery of the fan wheel of circular, curved or rectangular form in section and the edge of the casing on the .suction side is turned inward over the periphery of the blades toward the positive end of the fan wheel the terminal edge of said turned in portion .forming a circle of greater diameter than that of the intake end of the fan wheel and extending if required as far as the negative portionof the fan blades.

The accompanying drawings show some constructions of casinglembodyingthe present invention. u n Figure 1 is a cross section of a single i'ntake tan. Fig. 2 is a side elevation of Fig.

1. Fig. 8 is a modification of asingle intake fan. Fig. 4 is a cross section of a double intake fan. Fig. 5 is a part 4sectional plan, (with fan dotted,) showing the lip Vor {iange a5.

According to the modiiicationshown in Fig. 1 the casin'g a is of such cross section that the part a. thereof which is contiguous to the positive end of the fan wheel, and is parallel therewith, or to the back of the fan in the casevof, a single intake fan, gradually curves outwardly toward the central part of the casing, and then inwardly as at a2 over toward and as far as (orabout) the plane of the negative or intake ends n of the blades, and, in its further extension a3 curves inward and back toward the positive end p of the fan wheel, the terminal edge a.4 of this curvature forming a circle of greater diameter than that of the intake end b of the fan wheel L and the said extension as extending iiiore or less over the intake end of the fan wheel. but not farther than the neutral part o of the blades, which is about midway of their axial length. An annular space c is thus left between said terminal edge and the periphery of the wheel b, through which space c an induced current of fresh air can pass as indicated by the arrows into the casing from the suction side, and a part of which current can enter centripetally into the spaces or ports between the negative ends of the blades as described in my prior patent, while the remainder of the induced current flows axially along the outer surface of said negative end, and joins in, or

combines with the air which is whirlingy around, and along the concave interior circumference of the casing, as well as with the fresh air which is being directly discharged from the positive end p of the fan wheel, and the induced air thus admitted adds to the' volume being discharged out of the casing, Without said induced air having to pass throughthe fan wheel b at all. By this improved construction of the inclosing casing` around the fan wheel, the additional volume of air admitted by induction, so increases the total volume dealt with, that a much smaller diameter of fan wheel can be employed for the required duty, than if all the air had to pass through the wheel itself, but` of course the velocity of discharge, or the pressure setup thereby, will only be a resultanti between that of the direct discharge from the fan wheel, and. the' volume of in i duced air, which is being ,admitted at atof said curvature is brought around, and

back to, the plane of the intake end of the fan wheel, `while still having the `circle c formed by saidterminal edge a4 greater than the periphery of the intake end of the Wheel, to admit the induced current of fresh air from the suction side as in the first hereinbefore described modification toward the positive end p ofthe fan wheel and in some cases said terminal edge a,4 of the casing may project past or be take end of lthe wheel as indicated in Fig. 5 so as to be parallel therewith all around, or only a part may be thus extended inward over the negative end of the fan, in the form of a lip or flange a5 which may project inward past said plane to any suitable distance, not exceeding say half the length of the blades, the part a6 of greatest projection being preferably contiguous to the. discharge outlet from the casing. According to this second modification, a larger area of dis` charge from. the casing can be obtained, without having to increase the over-all diameter of the casing, than when it is constructed in accordance with the first hereinbefore described modication.

The formation of the casing will be suitably modified in the case of a double intake fan and that portion of the casing which is coincident with the central plane of the fan wheel may be carried inward toward the fan wheel or not as may be required.

Fig; 4 shows one lconstruction applied 'to double intake fan wheel the central part of the casing being provided with an inwardly projecting flange f to properlydirect' the current of air leaving the central posltive` portions p p of the double fan wheel overv toward the intake ends ofthe blades..

'What I claim and desire to secure by Letters yPatent is y 1'. A casing in which the edge of the casing on'the suction side is turned inward over the periphery of the negative or intake end `of the 'fan blades toward the positive end 'of the fan wheel 'the terminal edge of said turned in portion forming a circle of greater diameter than that of the intake end of the fan wheel and constituting the inlet or eye to the casing. Y.

2. A kcasing havinga part of clrcular or curved section disposed radially beyond the' periphery of the fan wheel the edge of the casing on the suction side being turned inward yover 4the periphery of the negative or intake end of the fan blades toward the posiwithin the plane of the 111-,

tive end of the fan wheel the terminal edge of said turned in portion forming a circle f ofv greater diameter than that of the intake end of the lfan wheel and constituting the inlet or eye to the casing.

3. A casing for centrifugal fans andl A .pumps having a wall which is contiguous to the positive end of the fan Wheel and 'is approximately parallel therewith and which gradually curved outwardlyv toward the intake side of the casing and then inwardly over toward and approximately as far as the plane in which the negative or intake endsV of the blades revolve and in itsfarther extension curves inward and backftoward the positive endof the fan wheel, the terminal l edge of this vcurvature forminga circle of greater diameter than that of the intake end of the fan wheel, and extending more or less over the periphery thereof, but not farther than the neutral part o1 the blades., which is approximately mid-way of their axial length, an annular space. being left betweenv the said terminal edge and the periphery `of the wheel through which an induced current of air can pass into the casing' from the suction side.

-, AQA casing for centrifugal fans and 4pumps .having a wall which is contiguous to the positive end of the fanwheel and is approximately parallel-therewith and which gradually curves outwardly toward the intake side of the casing the casing being carried out beyond the plane in which the intake end of the 'fan wheel, lies, and then inwardly ovei` toward and approximately as far as the plane in which the negative or intake ends of the blades revolve, `the terminal edge of this curvature forming a circle of greater diameter than that of the intake end of the fan wheel, and extending more or less over the periphery thereof, but not farther than the neutral part of the blades,lwhich is a g proximately midway of their axial-lengt an annular space being left between sai terminal edge and the periphery of the wheel through which an induced current of air can side. l

' 5. A casing having a part of circular or curved section disposed radially beyond the periphery of the fan wheel the edge ofthe casing on the suction side being turned in-v ward over the periphery of the fan blades toward the ositive end of the fan wheel the terminal e ge of said turned ,in portion `forming a circle of greater diameter than that of the intake end ofthe fan wheel and constituting the, inlet or eye to the casing pass into the casing fromthe suction' said curvature of periphery of the fan Wheel the edge ofthe casing on the suction side being turned inward over the periphery ofthe fan blades toward the positive end of the fan Wheel and extending a distance not exceeding one-haltl the length of the fan blades, the terminal edge of said turned in portion forming a circle of greater diameter than that of the intake end of the fan wheel and constituting the inlet or eye to the casing.

7. A casing having a part of circular or curved section disposed radially beyond the periphery o' the fan wheel the edge of the easing on the suction side being turned inward over the periphery of the negative or intake end of the fan blades toward the positive end of the fan wheel, the terminal edge of said turned in portion forming a circle of greater diameter than that of the intake end of the fan wheel and 'constituting the inlet or eye to the easing part of the terminal edge of the casing is extended inward over the fan wheel in the form of a lip or flange, the part of greatest projection being preferably contiguous to the discharge outlet from the casing.

In Witness whereof, I have hereunto signed my naine in the presence of two subscribing witnesses.

SAMUEL CLELAND DAVIDSON.

W'itnesses JOHN JOHNSON, HUGH TAYLOR COUTLEB. 

